The field of the invention relates to a system for estimating fuel consumption in a vehicle equipped with an internal combustion engine, using mass airflow and the air/fuel ratio, and in particular, to using this information for determining whether the performance of a fuel level sensor is degraded.
Vehicles typically have a fuel level sensor for determining fuel levels and a fuel gage for displaying the information to the driver. There are also methods in place to provide the driver with miles to empty and miles per gallon estimates. Also, there is usually a diagnostic system in place to inform the driver of out of range fuel sensor degradations. In particular, if the fuel level sensor is stuck in high or low, an indicator is provided to the driver.
The inventors herein have recognized a disadvantage with using a fuel level sensor diagnostic method based only on out of range checks. For example, if expected fuel level sensor voltage limits are 0.5-4.5V, the driver will be informed when the voltage level falls below 0.5V or above 4.5V. Using this approach, one cannot determine if the fuel level sensor is inaccurate or stuck within a normal operating range. This may provide the driver with degraded information and may cause inconvenience.
An object of the present invention is to provide a method for diagnosing a fuel level sensor of a vehicle equipped with an internal combustion engine.
The above object is achieved and disadvantages of the prior approaches are overcome by a method for estimating vehicle fuel consumption and diagnosing a fuel level sensor coupled to vehicle. The method comprises determining a first estimate of fuel consumed using vehicle operating conditions; determining a second estimate of fuel level based on said first estimate; reading the fuel level sensor; and comparing said second estimate with said reading to determine whether said sensor is functioning.
In another aspect of the invention, the method comprises estimating a first fuel consumed using vehicle operating conditions; estimating a second fuel consumed based on the fuel level sensor; and determining that the fuel level sensor is degraded based on comparing said first fuel consumed and said second fuel consumed.
An advantage of the above aspect of the invention is that a robust test for in-range failures of the fuel level sensor is developed, which decreases driver inconvenience. Another advantage is that a more precise method of fuel consumption calculation is achieved. In another aspect of the invention, the method also accounts for refueling by customers and memory resets by service technicians.
Other objects, features and advantages of the present invention will be readily appreciated by the reader of this specification.